Utility-scale electricity storage systems based on a variety of technologies have been installed all over the world during the past 30 years. The earliest installations were pumped hydro plants (global installations) or used low-speed flywheels (in Germany) or lead-acid batteries (in the UK). Only recently have other storage technologies started to gain more acceptance. The graph below shows, by technology, energy storage that has been installed or is planned for installation in the next five years It shows only those systems for which both energy and power numbers were available. For example it only shows ~10% of pumped hydro systems as energy content is often not available.
Revised April 2010